In medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, a contraindication is a condition or factor that serves as a reason to withhold a certain medical treatment.

Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action. For example, children and teenagers with viral infections should not be given aspirin

Aspirin

Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...

 because of the risk of Reye's syndrome

Reye's syndrome

Reye's syndrome is a potentially fatal disease that causes numerous detrimental effects to many organs, especially the brain and liver, as well as causing a lower than usual level of blood sugar . The classic features are liver damage, aspirin use and a viral infection...

, and a person with an anaphylactic

Anaphylaxis

Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...

 food allergy

Food allergy

A food allergy is an adverse immune response to a food protein. They are distinct from other adverse responses to food, such as food intolerance, pharmacological reactions, and toxin-mediated reactions....

 should never eat the food to which they are allergic. Similarly, a person with hemochromatosis should not be administered iron preparations.

Other contraindications are relative, meaning that the patient is at higher risk of complications, but that these risks may be outweighed by other considerations or mitigated by other measures. For example, a pregnant woman should normally avoid getting X-ray

X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

s, but the risk may be outweighed by the benefit of diagnosing (and then treating) a serious condition such as tuberculosis

Tuberculosis

Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

. Relative contraindications may also be referred to as cautions, such as in the British National Formulary

British National Formulary

The British National Formulary is a medical and pharmaceutical reference book that contains a wide spectrum of information and advice on prescribing and pharmacology, along with specific facts and details about all medicines available on the National Health Service , including indication,...

.

See also

• Classification of Pharmaco-Therapeutic Referrals
  Classification of Pharmaco-Therapeutic Referrals
  The Classification of Pharmaco-Therapeutic Referrals is a taxonomy focused to define and group together situations requiring a referral from pharmacists to physicians regarding the pharmacotherapy used by the patients. It has been published in 2008...
  
  
• Drug reaction testing
  Drug reaction testing
  Drug reaction testing uses a genetic test to predict how a particular person will respond to various prescription and non-prescription medications...
  
  
• Indication (medicine)
  Indication (medicine)
  In medicine, an indication is a valid reason to use a certain test, medication, procedure, or surgery. The opposite of indication is contraindication.-Drugs:...